1. Field of the Invention
The invention relates to a control method for extender, and more particularly, to a control method for extender used in a two-way transmission of information.
2. Description of Prior Art
Please refer to FIG. 1. FIG. 1 is a block diagram of prior art of video/audio extender. A video/audio extender 100 includes a transmitting unit 102 and a receiving unit 104. The transmitting unit 102 may electrically connect to the receiving unit 104 by a network cable or optical fiber, for example. The transmitting unit 102 may electrically connect to a host device 106 such as a computer host or other Video/Audio player. The receiving unit 104 may electrically connect to an audio device 110 and a display device 112.
The host device 106 sends a video/audio signal 108 to the transmitting device unit. The transmitting unit 102 sends the video/audio signal 108 to the receiving unit 104. The receiving unit 104 sends the video/audio signal 108 to the audio device 110 and the display device 112. Finally, the audio device 110 and the display device 112 play the video/audio signal 108.
Please refer to FIG. 2. FIG. 2 is a block diagram of prior art of video/control device extender. A video/control device extender 200 comprises a transmitting unit 202 and a receiving unit 204. The transmitting unit 202 may electrically connect to the receiving unit 204 by a network cable or optical fiber, for example. The transmitting unit e 202 may electrically connect to a host device 206 such as a computer host or other Video/Audio player. The receiving unit 204 may electrically connect to a control device 208 (such as a mouse or keyboard), an audio device 212 and a display device 214.
The control device 208 sends a control signal 210 to the receiving unit 204. The receiving unit 204 sends the control signal 210 to the transmitting unit 202. The transmitting unit 202 sends the control signal 210 to the host device 206. Finally, the control signal 210 is processed by the host device 206 and played by the audio device 212 and display device 214.
Currently, the video/audio device extender and video/control device extender are widely used in various applications. However, the prior art of circuit layouts of the video/audio device extender and video/control device extender are used in a single way transmission of information. It is easy to cause poor image quality because the transmitting unit fails to correctly obtain an extended display identification data (EDID) of a display device. Also, because the transmitting unit fails to correctly obtain the peripheral data of a control device, the control device can not be operated smoothly. In case of a two-way transmission of information, it may require to add the number of cables, have complicate circuit layouts or decrease some previous function to achieve the purpose of a two-way communication. Therefore, it is inconvenient and complicate.